Re: [AMRadio] Previous Text
On 6/5/06, Brian Sherrod <[EMAIL PROTECTED]> wrote: we just need to use common sense Exactly. No sense making mountains out of mole hills. 73 Mark K3MSB
Re: [AMRadio] ground sticks again
Hey Dennis did you ever forget to remove a clip lead and hit the HV button? I'll plead guilty to that one. The old RCA klystron-based UHF transmitters ran 18-25 KV, depending on the model with supplies that were capable of delivering a dozen or so amps all day, every day. They were huge rigs that you walked inside of to service. As soon as you were inside, the first thing you did was use the shorting stick on all of the capacitors. Next, you hung the stick on the HV bus coming off the rectifier stack. You then used an additional shorting stick to ground out whatever part you were about to work on. More than once I hit HV on with the stick still in place. It was no big deal. The breakers popped, you reset everything and tried again. Not once did I ever see any real damage done to one of those rigs by forgetting to remove the shorting stick before beam on. It's also interesting to point out that all of those transmitters was equipped with a special relay gizmo thingy that would short out high volts when the beam was turned off. In all the 30 years off and on that I've worked on UHF television transmitters I never once experienced the big bang with the shorting stick. The occasional arc and spark, but never wound up discharging the full load. I know others who were not so fortunate, but lived to tell about it thanks to their shorting stick. I should also point out that every UHF rig that I've ever seen has some sort of interlock that automatically grounds out the HV whenever any dangerous area is open. In spite of such precautions, a shorting stick was always provided and always used before sticking one's hands inside. Even so, I always felt a little squeamish whenever I first reach inside. I can assure you that I've never, ever worried about popping a capacitor. As far as I am concerned, using the shorting stick is a part of normal operation. Any component that dies as a result was poorly designed in the first place. Alan WA2DZL
RE: [AMRadio] ground sticks again
I knew someone would bring that up. No, I never did forget to remove the clip leads. If I had forgotten, then either the overload relay would kick out the HV or the transmitter would have blown a fuse - either of which could easily be repaired..if you're still alive. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Wilhite Sent: Monday, June 05, 2006 7:05 PM To: Discussion of AM Radio Subject: Re: [AMRadio] ground sticks again Hey Dennis did you ever forget to remove a clip lead and hit the HV button? 73 Jim W5JO > > When I worked on a transmitter, I always kept a bunch of new clip leads > available at the transmitter site. After touching all the high voltage > points in the transmitter with the shorting stick, I would keep the > shorting > stick on each high voltage point while I used a clip lead to short the > point > to ground. The transmitter would stay that way until I was ready to > return > it to service. > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] ground sticks again
Hey Dennis did you ever forget to remove a clip lead and hit the HV button? 73 Jim W5JO When I worked on a transmitter, I always kept a bunch of new clip leads available at the transmitter site. After touching all the high voltage points in the transmitter with the shorting stick, I would keep the shorting stick on each high voltage point while I used a clip lead to short the point to ground. The transmitter would stay that way until I was ready to return it to service.
RE: [AMRadio] ground sticks again
Amen to that Dave! In an earlier life, I was a Broadcast Engineer for about 15 years. During that time, I worked on everything from 250 watt AM to 50KW AM and on to 100KW ERP FM transmitters. I've worked with virtually all the known manufacturers gear from Raytheon to RCA and Collins to Continental (one in the same). Not once, not ever, did I see a grounding stick with a built in bleeder resistor in any of those transmitters. And there was a very good reason for that - none of the manufacturers wanted to deal with the lawsuit that would have resulted from an Engineer being killed by such a dangerous idea. When I worked on a transmitter, I always kept a bunch of new clip leads available at the transmitter site. After touching all the high voltage points in the transmitter with the shorting stick, I would keep the shorting stick on each high voltage point while I used a clip lead to short the point to ground. The transmitter would stay that way until I was ready to return it to service. I would much rather know instantly (from the spark and noise) that I have an open bleeder resistor. I can always go buy another pair of underwear. Bottom line - There is no component, no matter how rare or expensive, that is worth a human life. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of david knepper Sent: Monday, June 05, 2006 2:55 PM To: Discussion of AM Radio Subject: Re: [AMRadio] ground sticks again If anything, these discussion only point out that ownership of a broadcast transmitter is one thing; but it is another to modify, restore, and operate one by only those who know what they are doing! Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
[AMRadio] FS: Ferris, Heathkit, Millen, RU-15, BC-652A, BC-348, T-17, R-390 Parts, PRC-10, Test Gear, Literature
For Sale: Boatanchors, Literature and Related Ferris 22A Signal Generator. Covers 85kc to 30mc in 7 bands. Metered output is adjustable from 0 volts to about 1.5 volts in microvolt steps. Selectable modulation. Nice steel back wrinkle cabinet. Dial window has yellowed and cracked. Top-quality pre-war HF signal generator. Seems to be all original. Untested and as-is. $30 Heathkit IG-102 RF Signal Generator. Covers 110kc to 110mc in 6 bands. No metering. Looks great. All original. Untested. As-is. $20 Heathkit Sixer HW-29A lunchbox 6-meter transceiver. Needs some cleaning but will clean up to excellent original condition. With original power cord, original manual, and original microphone. $50 James Millen 90652 Solid State Dipper covering 1.7mc to 300mc in 7 bands. With all coils, original manual and original plastic carry-case with the green Millen “gear” logo on the side. Foam rubber holding coils has deteriorated and will need replaced at some point, though it is useable as it is. Beautiful condition. $50 Homebrew electronic antenna switch--at least I think that’s what it is. It’s a small aluminum case with a single 12AU7A and associated parts inside. The front panel has a band switch marked for 80-10 mters, a TUNE control (variable cap), a power switch and pilot light. On the back are 3 SO-239 connectors, one marked TX, one RX and one unmarked (presumably ANTENNA). There’s an AC line cord and a GROUND connection. Untested. As-is. Will probably come right up. $12 plus $8 flat rate box Collins 70E-2 PTO from the military ARR-15 transceiver--just the PTO in the shielded can with the 12SJ7 metal tube sticking out. None of the dial parts are present including the dial shaft. As-is. $8 Early WWII military radio receiver RU-15 with coil set CBY-47146A covering 200-400kc and 4.79 to 9.1 mc in 2 bands. With MC-127 spline tuning knob. This also has the CBY-23096A reciever switch box and a wiring harness that connects it to the RX using the original connectors. The wiring comes out to a six-pin tube socket for connection to your power power supply (no power supply is included). This has come paint flaking but is an excellent example of an early war aircraft receiver. Very classy. $125 Leeds and Northrup decade resistor. This is one of those classic wooden test boxes with scads of brass fittings on top of a hard rubber panel. The circular contacts are arranged in 5 rows of pairs labeled 0 through 9 and brass pegs are provided, that when placed properly, can select any resistance from 0.1 ohm to 10,000 ohms. Unfortunately, I think there should be 5 brass pegs and there are only 4. The unit is in beautiful shape with no corrosion or rust and wood excellently finished. The brass tag says “Chem Dept 108 C.I.T.” which probablky stands for Carnegie Institute of Technology--the early name for Carnegie Mellon University here in Pittsburgh. As-is. $30 Another wooden Leeds and Northrup thing with a hard rubber panel. This is slightly larger than the one above. It has 2 huge nickel-plated binding posts on the left marked E.M.F. and two more on the right marked P. Both sets have polarity marked + and - . In the center of the panel is a rotary switch with 5 exposed contacts. The switch arm has a bar on it that makes sure that it makes one contact befor breaking the next. Three positions on the switch are marked 10 100 1000. The wooden box has ventilation holes so whatever is inside must generate heat when EMF is applied. Nice condition. No tag. $30 J-38 key. Some pitting and dirt. $10 Military WWII Signal Corps BC-652-A tank radio receiver covering 2-6mc in two bands plus a VLF band. This one has had an AC power supply built into the top section where the dynamotor was with on/off switch, fuse and line cord. Also one of the small knobs is wrong. The black has been oversprayed lightly so that the engraved markings around the controls are still visible. Overall, the look is good and close to original. $90 Military WWII T-17 microphone made by Western Electric in 1942. Metal. Good. Original. $22 Military WWII T-17 microphone made by Shure in 1943. Good original. Plastic. $18 Military R390/390A set of original covers--top and bottom. Good shape with the usual scrapes. $50 Military R390/390A set of original meters with the metal frames as used on the R390 but no mounting screws. Good. $50 R-390 (not A) parts available. I have a complete set of R-390 (not A) modules including the PTO, RF, IF, connecting cables, tubes, shields, gears, knobs, handles and all. Sell all or individual parts. Please inquire. Military WWII Signal Corps BC-348-R HF receiver covering 200-400kc and 1.5-18mc . The front panel is all original. This has had an AC supply built inside and has an AC line cord coming out the connector hole in the rear. With shock mount. Untested. As-is. Looks very good or excellent. $165 Another military WW
Re: RE: [AMRadio] ground sticks again
watch the discovery channel and see how helos are used to work Hot on hv xmission lines..way cool... farady shield underware??? - Original Message - .net> > > --- Donald Chester <[EMAIL PROTECTED]> wrote: > > >From: "Jim candela" <[EMAIL PROTECTED]> > > > > >Humans are expendable, but don't destroy them hard >Paul Courson/wa3vjb
Re: [AMRadio] ground sticks again
If anything, these discussion only point out that ownership of a broadcast transmitter is one thing; but it is another to modify, restore, and operate one by only those who know what they are doing! Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST
[AMRadio] A grounding stick idea
Wouldn't a solenoid, wound of say, 50 close-spaced turns of fairly heavy guage insulated wire, and wrapped/taped well (to resist the sudden mechanical forces deriving from the ampere-turns of the coil) - be a good compromise between 'dead-short' poultry-bars and the 'resistance' kind? The idea being that a step-function wavefront would encounter the reactance of the coil, damp itself a bit, ring back and forth, and still have a low-Z DC path to ground - kind of a "soft-start" approach. I do agree - I'd be leery of any kind of regular resistor (that I could easily lift) in that path of a hefty HV cap discharge - if not the first time, then how many subsequent blasts before the resistor changes impedance to the meg-ohm range? Another point: I have several TMs and training manuals from the Army, Navy, and Air Force. ALL of them show grounding sticks made of wooden dowels or 1X1 lumber, with the usual heavy braid and hooked 'business end'.As late as the mid 60s these are shown. Cheers John KB6SCO
[AMRadio] resistor grounding sticks available
Voila, resistor grounding sticks, very well made. This company (White Rubber Co) has lots of good devices for working safely around high voltage, esp power lines. Go to the bottom of the pages on this link: http://www.whitesafetyline.com/products/grounding3.html#rstvdschrghkprb > If > the Great Electron Gods had intended for capacitors to be discharged through > a > resistor (other than a bleeder) before working on a circuit, them he would > have made discharge sticks with built in resistors. I have never seen one, > have > you? 73 John K5PRO
Re: [AMRadio] PA set up using ant analyzer
The resonate plate load is the same for any class C amplifier, plate voltage divide by 2 times plate current. It is one half of the modulating inpedance. It is the same for a 6V6, 6AQ5 or a pair of 4-1000's.. Mike - Original Message - From: "uvcm inc." <[EMAIL PROTECTED]> To: "'Mike Dorworth, K4XM'" <[EMAIL PROTECTED]>; "'Discussion of AM Radio'" Sent: Sunday, June 04, 2006 11:12 PM Subject: RE: [AMRadio] PA set up using ant analyzer Does it matter the type of tube, 833 or 592 r Thanks Brad -
RE: [AMRadio] ground sticks again
--- Donald Chester <[EMAIL PROTECTED]> wrote: > > > > > >From: "Jim candela" <[EMAIL PROTECTED]> > > >Humans are expendable, but don't destroy them hard > to find capacitors! :-) > > It's no less safe to discharge them gently, first > using a resistor then > discharging directly, than discharging them with a > "bang." > > Besides, if you discharge them with a "bang" a tiny > piece of molten metal > could hit you in the eye. > > I don't normally wear safety goggles while working > inside a transmitter. > That itself could be a hazardous distraction. > > Don k4kyv > > > Don, All good points. I was trying to put this into perspective where safety concerns must prevail over equipment concerns every time. That said, we can design gear and write safety policies to achieve both. I like to put a large wire wound resistor in series with a capacitor bank before the DC goes to a RF PA or modulator. It could be a 50 watt 50 ohm resistor. This will have little impact to normal operation, but in case of a fault by either a chicken stick, or a internal tube arc, the peak current is defined as I = E/R instead of near infinity and beyond. This approach will protect your precious capacitors too. A bleeder should be used before the series resistor with something like a 5 minute discharge time. So combine this with a sign saying to wait 5 minutes or longer after removing AC power, and to short out the B+ with a chicken stick. When done, safety requirements are met. Of course any Yahoo can still get around, and either kill themselves, and or destroy the rig. It's hard to make something idiot proof. At the company I work for, some Yahoo used a chicken stick to defeat a gravity assisted grounding bar. Then a 90kv 100ma supply turned on, and arced to his foot, and out his right butt cheek into the floor. His life was saved when a metal door slowly closed, and interrupted the arc, which allowed him to limp away. The need to defeat interlocks did not exist, and the whole issue was he was not aware of the danger, and work arounds so that he didn't need to risk his life. At an old job I once had, an engineer (a ham to boot) would routinely isolate his chair, and workstation, and go up to 40,000 volts to work on something HOT. When he was done, he'd use a fiberglass rod to hit the HV off button, and then take a 200 meg-ohm resistor in his hand and touch the far end to earth ground. Then he'd step down, and go do something else. He did that all the time. You didn't dare get too close to him, or try to shake his hand! I saw him get nailed one day where he was at 40kv, and reaching up to something at 150kv, and he got too close. I saw no less than 6 long snaps into his hand as he waited for the Hippotronics 1D21 thyratron to kick in, and disable the supply. He then stepped down and walked away...white as a ghost. Jim JKO > AMRadio mailing list > Home: > http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul > Courson/wa3vjb >
Re: [AMRadio] ground sticks again
Reply-To: Discussion of AM Radio How do you intend to handle the resistor while doing the discharging? You are still going to need a shorting stick. It is much better to take the slight chance of discharging the >cap the direct way than messing around with some Rube Goldberg resistor arrangement. If the Great Electron Gods had intended for capacitors to be discharged through a resistor (other than a bleeder) before working on a circuit, them he would have made discharge sticks with built in resistors. I have never seen one, have you? It is very easy to build one. Use something like a 500-1000 ohm 20-50 watt wirewound resistor. Rigidly attach it to an insulated rod, on the same end that you use to touch the HV. Better still, use a large enough resistor and small enough rod that you can pass the rod through the resistor, and clamp it down. Make sure everything is rigid enough that the resistor isn't dangling. To be safe, short out the capacitor directly after first using the resistor, just in case Murphy strikes and the discharging resistor opened up just as you discharged. This can most easily be done with a second, more normal shorting stick. I suppose one could get fancy and build a special shorting stick with a resistor and a direct shorting tip, in a mechanical arrangement that would resemble a Wouff-Hong, but to me it's easier to just have the shorting resistor on hand along with the regular stick. I don't use a resistor normally, after observing the expected drop-down of the plate voltage when the transmitter is shut off. Since the likelyhood that the capacitor is still charged is already remote, I am willing take the risk of blowing the capacitor or shrapnel in my face. But I NEVER KNOWINGLY DIRECTLY SHORT A FULLY CHARGED HV CAPACITOR. There's a lot of energy in that discharge, which can in itself can be dangerous, as well as ruin the capacitor. The resistor will feel warm to the touch after the discharge, even though it may be of very short duration. I once destroyed a 25 mfd 4000 volt capacitor by shorting it with a screwdriver. I opened the case and discovered that the flexible wire lead going from the guts of the capacitor, no larger than maybe #16, made from tinned, bare, twisted copper wire, had opened just like a fuse. I resoldered the wire and attempted to put the capacitor back together, but it still didn't work. The wire was probably vaporised at the other end too, and I didn't care to dig into the PCB saturated guts of the cap, so I just took the whole thing to the county's next "household hazardous waste disposal day," and was relieved when they took it without asking me what it was. Transmitting caps are not that hard to find, not that expensive. You can find them at nearly every hamfest. At the Manassas, VA hamfest yesterday, there were 2 large piles of them at one vendor in the flea market and he would almost pay you to take them home. People said the same thing about VT4-C/211's, 2A3's, 6B4G's, 845's, and UTC LS-series audio transformers just a few short years ago. Don k4kyv
Re: [AMRadio] Previous Text
On 6/5/06, Todd, KA1KAQ <[EMAIL PROTECTED]> wrote: I had a lengthy back and forth with Paul on this and tried to explain what Geoff and others have said here. I do agree with Paul's premise that we're all capable of keeping up and reading between the lines, and in most cases I'm sure that is sufficient. The main thing that really miffs me is when someone posts a long list of things for sale and someone responds back to the list wanting to buy a certain item and also includes the entire long list of things for sale. While on that subject; I would like to ask that from this point on, all sellers include at the top of their list for potential buyers to reply _directly_ to them only. I don't mind people posting items for sale, as it's a good way for us to get first notice to good ol' vintage stuff before it goes to ePay. Regarding the inclusion of discussion text from a previous poster, I say include (if need be) the previous posters comments in regard to your response only. If you have a response to several comments made by the previous poster then use the "top posting" method, cascading through the original text much like Geoff/OMR has done in recent replies. Everyone who has replied to this thread has a valid point, and we just need to use common sense on how we make our replies. Back in the old days, you would have been scolded about including too much original text due to bandwidth over the net. Still a valid point, but not near as critical an issue nowadays. We have a great group here, and I know we (me included) all screw up from time to time, but I see far less "screw-ups" here than I do on all the other lists and forums I belong to. You can't help but love the AMRadio list! 73, Brian / w5ami
RE: [AMRadio] ground sticks again
From: "Jim candela" <[EMAIL PROTECTED]> Humans are expendable, but don't destroy them hard to find capacitors! :-) It's no less safe to discharge them gently, first using a resistor then discharging directly, than discharging them with a "bang." Besides, if you discharge them with a "bang" a tiny piece of molten metal could hit you in the eye. I don't normally wear safety goggles while working inside a transmitter. That itself could be a hazardous distraction. Don k4kyv
[AMRadio] Vac Cap
In a Pi configuration for the BTA-1R2 would a 10kv vacuum variable be sufficient for the input variable? My calculations indicate a 12kv would be ideal and a 15kv would be best, however, I have located a 10kv at a decent price. My intentions are to set it up for 75 meters at first, but would like to install components capable of going down to 160 if later desired. So, I figure a 100pf - 300pf input variable should work. For the output I figure a 1100pf - 2400pf would do the trick. If I can use a vacuum relay to switch a tap on the coil I think it will work. What do ya'll think? Rick/K5IZ
Re: [AMRadio] Previous Text
On 6/4/06, VJB <[EMAIL PROTECTED]> wrote: When I told people whom I've recently busted for including a distracting amount of previous text in their responses, I mentioned how I don't subscribe to any reflectors other than this one. I had a lengthy back and forth with Paul on this and tried to explain what Geoff and others have said here. I do agree with Paul's premise that we're all capable of keeping up and reading between the lines, and in most cases I'm sure that is sufficient. That someone would actually complain to a list admin about quoted text being used struck me more along the lines of those who are disinterested in a particular thread and tell people 'enough, it's time to move on' just because they're bored. This always struck me as a bit self-righteous and selfish. However, over-quoting or simply hitting the 'reply-all' key without doing any editing as some prefer to do is just plain lazy and rude to all. I suspect this is where the real problem lies. And of course, some of us occasional post a reply in haste and forget to delete or trim. I've been guilty of this, but try hard to do it 'right'. Which gets back to the initial thrust of defining what is 'right'. I've never felt terribly comfortable trying to paraphrase someone else's words by using my own, probably because of getting my head bitten off for it in the past on some other list, board, or whatever. I do trim the post down to *only* the relevant sentences for context, even though it takes more time than just hitting 'reply'. So for me, a good middle ground for this medium lies between the "none" or "all" arguments. I do think most all of us do a very good job of this, although it's not unheard of to slip. I also believe that Paul's request to be more concise and paraphrase is a valid one, although like others, I feel more comfortable using the original poster's own words. Beyond these words and perhaps the original poster's name or call, I see no reason for headers or excess text to be included with any reply to a thread. It's just too easy for it to snowball as the thread grows and more folks repost the same text over and over. This is not only distracting, it's very annoying. And as I also told Paul, this is the best list I've ever been on with respect to the way we conduct ourselves and treat others. The fact that Paul and Brian seldom have to slap anyone down or even bring things like this up, is proof. de Todd/'Boomer' KA1KAQ
Re: [AMRadio] ground sticks again
In a message dated 6/5/2006 10:12:06 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: > He wasn't too bright. > Izzat what they call a dim wit? 73, John, W4AWM
Re: [AMRadio] ground sticks again
Now that is real wisdom! My shed, shack and junk room will attest to the fact that I follow that credo to the letter! Rick W5OMR/Geoff wrote: The parts collectors creedo is: 'Tis far better to have and not want, than to want, and not have."
Re: [AMRadio] ground sticks again
If I could add my "two cents" to this discussion. Any ham who has the slightest thought that a large oil filled capacitor is charged should bleed the voltage to ground through a 100K resistor, acting as a bleeder resistor. By the way, be very careful not to assume that your bleeder resistor is functional. Lots of folks, including myself, got nipped by a bleeder that opened up! Thank goodness it was only a few hundred volts but what if A shorting stick should be in evey hamshack. The one that I have is made from a phenolic rod about a foot long with a insulated copper braid with a clip attached to a hook rod at one end that I drape over the filter capacitors when working on the amplifier. It was issued to me when I was in the Air Force working on 5 KW transmitters. If the sergeant saw you without your "Jesus stick" you might get your butt kicked. Crazy story: I had a friend who used to charge up a 100 mfd/4000 volt oil filled capacitor to see how long it would stay charged!! He wasn't too bright. Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST - Original Message - From: <[EMAIL PROTECTED]> To: Sent: Monday, June 05, 2006 9:42 AM Subject: Re: [AMRadio] ground sticks again In a message dated 6/5/2006 0:25:48 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: it can ruin the capacitors with excessive instantaneous current surges. Better to first discharge through a resistance to limit the discharging current, then apply the "coup de grace" by shorting directly. How do you intend to handle the resistor while doing the discharging? You are still going to need a shorting stick. If the initial charge opens the resistor, tyou are still going to have a huge discharge when tou roun the cap directly. It is much better to take the slight chance of discharging the cap the direct way than messing around with some Rube Goldberg resistor arrangement. If the Great Electron Gods had intended for capacitors to be discharged through a resistor (other than a bleeder) before working on a circuit, them he would have made discharge sticks with built in resistors. I have never seen one, have you? Transmitting caps are not that hard to find, not that expensive. You can find them at nearly every hamfest. At the Manassas, VA hamfest yesterday, there were 2 large piles of them at one vendor in the flea market and he would almost pay you to take them home. 73, John, W4AWM __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
Re: [AMRadio] ground sticks again
[EMAIL PROTECTED] wrote: Transmitting caps are not that hard to find, not that expensive. You can find them at nearly every hamfest. At the Manassas, VA hamfest yesterday, there were 2 large piles of them at one vendor in the flea market and he would almost pay you to take them home. You probably should have gotten some extras then, eh? The parts collectors creedo is: 'Tis far better to have and not want, than to want, and not have." -- Driving your AM Rig without a scope, is like driving your car at night, without headlights. (K4KYV) -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] ground sticks again
In a message dated 6/5/2006 0:25:48 AM Eastern Daylight Time, [EMAIL PROTECTED] writes: > it can ruin the capacitors with excessive > instantaneous current surges. Better to first discharge through a > resistance to limit the discharging current, then apply the "coup de grace" > by shorting directly. > How do you intend to handle the resistor while doing the discharging? You are still going to need a shorting stick. If the initial charge opens the resistor, tyou are still going to have a huge discharge when tou roun the cap directly. It is much better to take the slight chance of discharging the cap the direct way than messing around with some Rube Goldberg resistor arrangement. If the Great Electron Gods had intended for capacitors to be discharged through a resistor (other than a bleeder) before working on a circuit, them he would have made discharge sticks with built in resistors. I have never seen one, have you? Transmitting caps are not that hard to find, not that expensive. You can find them at nearly every hamfest. At the Manassas, VA hamfest yesterday, there were 2 large piles of them at one vendor in the flea market and he would almost pay you to take them home. 73, John, W4AWM
Re: [AMRadio] PA set up using ant analyzer
In a message dated 6/4/06 8:13:09 PM, [EMAIL PROTECTED] writes: > Does it matter the type of tube, 833 or 592 r > What's a "592 r" tube? Can't find it in Fathauer or Sibley. See references to a 592 and a 592/3-200A3 but neither looks like a substitute for an 833. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] CORRECTION
In the Gates BC1-T, there are two 833A's, driven by two 807's. So I suppose you could say that each 833A is driven by an 807. Don k4kyv
RE: [AMRadio] ground sticks again
Humans are expendable, but don't destroy them hard to find capacitors! :-) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Donald Chester Sent: Sunday, June 04, 2006 11:25 PM To: amradio@mailman.qth.net Subject: RE: [AMRadio] ground sticks again >Grounding capacitors can be unfriendly, but lifesaving in the longer term. Not only unfriendly, but it can ruin the capacitors with excessive instantaneous current surges. Better to first discharge through a resistance to limit the discharging current, then apply the "coup de grace" by shorting directly. Large oil-filled transmitting capacitors are expensive and hard to find. Like tubes, we need to take extra precautions to preserve them as long as possible. I suspect that with the advent of solid state equipment and lower operating voltages, that HV capacitors in a few years will be as hard to find as most transmitting triodes are today. Don k4kyv __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.8.1/355 - Release Date: 6/2/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.8.1/355 - Release Date: 6/2/2006
[AMRadio] AM songs (audio clips)
Check out the two AM songs that are presently up on the AM Forum. One it titled "Come All Ye AM'ers," and the other, "Fee Cee's Law" Click on the URL (or copy and paste): http://amfone.net/Amforum/index.php?topic=7733.msg56781#msg56781 Now scroll down to the 4th and 8th postings, and click on the links. I saved both songs to my hard drive. Don K4KYV ___ This message was typed using the DVORAK keyboard layout. Try it - you'll like it. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/
RE: [AMRadio] ground sticks again
Grounding capacitors can be unfriendly, but lifesaving in the longer term. Not only unfriendly, but it can ruin the capacitors with excessive instantaneous current surges. Better to first discharge through a resistance to limit the discharging current, then apply the "coup de grace" by shorting directly. Large oil-filled transmitting capacitors are expensive and hard to find. Like tubes, we need to take extra precautions to preserve them as long as possible. I suspect that with the advent of solid state equipment and lower operating voltages, that HV capacitors in a few years will be as hard to find as most transmitting triodes are today. Don k4kyv
